Speedometer



March 9, 1937.

R. o. HELGEBY SPEEDOMETER 'Filed Feb. 27, 1935 Patented Mar. 9, 1937UNITEDv STATES PATENT OFFICE SPEEDOMETER poration of DelawareApplication February 27, 1935, Serial No. 8,422

1 Claim.

This invention relates to measuring instruments. It has been designed asan improvement in a so-called speedometer as used on vehicles.

An object of the invention is to obtain an improved instrument which maybe manufactured at a reduced cost.

A further object consists in a simplification of the assembly of theparts.

A further object is 'a lessening of the cost of the die cast supportingelement.

A still further object is an improvement in the adjustment of thetension of the hair spring which is used to bias the pointer to zeroreading.

The novel structure for the attainment of the above and other objectswill be understood from the following description.

In the drawing:

Fig. l is a longitudinal sectional view.

Fig. 2 is a perspective of an assembly adapted to be secured to the diecast support.

Fig. 3 is a perspective of the die casting and a part of the housing indisassembled relation.

Fig. 4 is a section on line 4 4 of Fig. 2.

Fig. 5 is a sectionv on line 5-5 of Fig. 2.

In the above figures numeral II designates a base, preferably made bydie casting. It has a stem I3 apertured as at I5 for receiving a drivingcable, not shown. The cable end is connected in any conventional waywith a rotor shaft i'l. The stem I3 is threaded as at I9 for engaging aconventional drive cable housing, also not shown.

The casing to house the instrument is marked 2|. The die casting carriescertain indicating members such as figure wheels 23. The dial plate 2'Iwhich is rigid with the casing is provided with an opening 25, whichopening must be so positioned as to render wheels 23 visible through theglass cover 29. It is therefore necessary that both the wheels and thecasing be accurately positioned relatively to the die casting. Forassembling the die casting and casing in this predetermined relativeposition the stern I3 is cast with a lug 3| designed to enter a notch 33in the adjacent wall of the casing as shown in Fig. 3. It will beapparent that this solves the problem of assembly of these two parts.The parts are readily engaged to accurately position the casing so thatthe dial opening 25 is deii- 50 nitely located relatively to the diecasting. If

provision be made, as it is and as will be explained, for similarlyaccurately positioning the assembly of wheels 23 relative to the diecasting,

a, quick and accurate complete assembling proc- 55 ess is insured.

Fig. 2 shows a field cup 35 having a flange 3l. The flange has aplurality of openings 39 through which extend fastening means 4Ithreaded into threaded openings 40 in the die casting I I. The openings40 may also receive the screws by which the casing 2| is secured to thebase or casting II. The flange 3l around the opening 39 is depressedinto the form of a sleeve as at 43 to t in'a recess 45 of the diecasting. These sleeve portions 43 and the recesses 45 accurately locatethe field cup 35 relative to th'e die casting so that it is onlynecessary to assemble the parts with the sleeve portions in the recessesto insure a predetermined relative position of these parts. The cup 35is preferably a stamping as indicated by the drawing.

Welded as indicated at 4l to the bottom of the cup is a U-shapedstamping 49 having upstanding arms 5I and 53. A bridge piece 55 extendsacross the arms 5I and 53 and is welded to angular extensions 5lthereof. The bottom of the inverted cup 35 is apertured at 59 and thestamping 49 has a somewhat smaller registering opening 6I.

Within the field cup 35 the rotor shaft Il carries a magnet 63 securedthereto in any preferred manner. The shaft Il is shown as having ashoulder 65 upon which the magnet rests. Above the magnet is atemperature compensating plate El. The extreme end of the rotor shaft isrecessed to support suitable. shaft bearings, indicated by nuineral 69,for a spindle 1I. The metal around the recess is spun over to hold theparts in assembled relation. This is illustrated at '13. Secured to thespindle II within the cup 35 is a cup-shaped rotor element l5. Theseparts operate in the manner well known in the magnetic speedometer artand need no further explanation.

For adjusting the conventional return spring the following expedient isemployed. The spindle has secured thereto at 'lll one end of a zerobiasing spring Il. 'Ihe outer end of the spring is secured at 'I9 to atongue 8| turned up from a plate 83. The plate 83 rests upon the bottomof the clamping 49 and is bowed slightly as shown by Fig. 5. It has acentral opening, the metal surrounding the latter being deflected toform a short sleeve extending through the opening 6I in the bottom 49 ofthe U-shaped stamping and is then bent over as at 85 to form a bearingengagement and holding the bowed surface with sufficient resiliency toresist but not prevent rotation. In this way the tension of the hairspring may be adjusted by rotating the plate 83 but the resilience issuch that the plate will be retained in positions of adjustment.

The bridge piece is apertured to receive a side bearing 8l for thespindle 1|. Outside the dial plate the spindle carries a conventionalpointer 89.

Between the several gure Wheels are conventional transfer pinioncarriers marked 9|, each of which has a radial notch to engage an arm 91turned up from the base of the U-shaped stamping. The assembly of figureWheels 23 is carried on a shaft 93 supported in the walls 5| and 53. Theposition of the shaft 93 and its wheels relative to the die casting isvdenitely determined by the expedient shown in Fig. 4 and represented bynumerals 4|, 43, and 45. the cup 35 and the stamping 49 are securedtogether, and since the shaft 93 is carried in the l stamping 49, itWill therefore be clear that no skill is required in accuratelyassembling the parts. The expedient of Fig. 4 definitely fixes theposition of the wheels 23 relative to the die casting and the expedientof Fig. 3 similarly locates the casing relative to the die casting.

No novelty is involved in the mechanismfor driving the figure wheels.There are shown gear teeth 99 on the rotor shaft. These teeth drive aworm shown only by its extreme end |9| in a bearing |03. At |05 is abearing opening for a second worm, also not shown, and driven by thefirst Worm. -The second worm extends axially. For its accommodation anotch is out in the flange 31 atl I9? and alsoa bowed part |09 is formedin wall 53. The end of the vsecond Worm enters a bearing hole inthebridge'55. This second worm is geared to an idler pinion, notv shown,but

, plained above.

SinceV rotatable on a, pin ||3 projecting inwardly from Wall 53. Thisidler drives a pinion (also not illustrated) on the shaft 93 forrotating the several wheels 23 in sequence in the usual way through theinstrumentality of pinions between the several wheels carried by plates9| anchored as ex- A Wire ||5 held in notches of wall 5| engages agroove (see dotted lines in Fig. 1) on shaft 93 to prevent axialmovement of the shaft. l

The die casting as compared with the similar casting in previousinstruments is reduced in size, partly by the omission of integral Sidewalls to support the shaft for the equivalent of Wheels 23. The diecasting is therefore reduced in cost. The stampings 49 and 55 are, ofcourse, very inexpensive andthe assembly expedients require no skill inputting together the several parts and housing them in the casing. Theresilient mounting of the hair spring arm 83 is a convenient means ofmaintaining the adjustment of the hair spring'l'l.

I claim:

In a measuring instrument, a base, an inverted cup, means to secure said`cup to said base, a U-shaped stamping secured to said cup, saidstamping having an opening between the arms thereof, a bridge terminallyunited to said arms, magnetic measuring mechanism within said cupincluding a spindle journaled therein, projecting therefrom andjournaled in saidbridge, a plate having a resilient bowedV surface, saidplate having a sleeve extending from. said surface and journaled in saidopening of said U-shaped stamping, and a Calibrating spring secured tosaid spindle and to said plate.

RALPH O. HIELGEBY.

